Atmospheric line

Atmospheric \At`mos*pher"ic\, Atmospherical \At`mos*pher"ic*al\,
   a. [Cf. F. atmosph['e]rique.]
   1. Of or pertaining to the atmosphere; of the nature of, or
      resembling, the atmosphere; as, atmospheric air; the
      atmospheric envelope of the earth.
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   2. Existing or occurring in the atmosphere.
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            The lower atmospheric current.        --Darwin.
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   3. Caused, or operated on, by the atmosphere; as, an
      atmospheric effect; an atmospheric engine.
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   4. Dependent on the atmosphere. [R.]
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            In am so atmospherical a creature.    --Pope.
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   {Atmospheric engine}, a steam engine whose piston descends by
      the pressure of the atmosphere, when the steam which
      raised it is condensed within the cylinder. --Tomlinson.

   {Atmospheric line} (Steam Engin.), the equilibrium line of an
      indicator card. Steam is expanded "down to the atmosphere"
      when its pressure is equal to that of the atmosphere. (See
      {Indicator card}.)

   {Atmospheric pressure}, the pressure exerted by the
      atmosphere, not merely downwards, but in every direction.
      In amounts to about 14.7 Ibs. on each square inch.

   {Atmospheric railway}, one in which pneumatic power, obtained
      from compressed air or the creation of a vacuum, is the
      propelling force.

   {Atmospheric tides}. See under {Tide}.
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